This revisionary study of Muslims living under Christian rule during the Spanish “reconquest” delves into the subtleties of identity under the thirteenth-century Crown rule of Aragon. Brian Catlos uncovers a social dynamic in which sectarian differences comprise only one of the many factors in the causal complex of political, economic and cultural reactions. Beginning with the final stage of independent Muslim rule in the Ebro valley region, he traces the subtle and often surprising transformation of Islamic society into mudéjar society under Christian domination.